The purpose of the study is to determine if ABT-751 will decrease tumors, and determine how long the tumor shrinkage can be maintained in patients with non-small cell lung cancer. Patients will receive ABT-751 by mouth daily for 21 days. Patients will be off drug for 7 days before starting the next cycle of drug.

Inclusion Criteria

• Stage IIIB or IV non-small cell lung cancer.
• Recurrent tumor following treatment with paclitaxel or docetaxel.
• Able to tolerate normal activities of daily living.
• Adequate bone marrow, kidney and liver function.

Exclusion Criteria

• Pregnant or breast feeding.
• Anti-tumor therapy within 4 weeks of the start of ABT-751 administration.
• CNS metastasis.